<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>CSS Masking: mask-position: position mask layer image</title>
    <link rel="author" title="Astley Chen" href="mailto:aschen@mozilla.com">
    <link rel="author" title="Mozilla" href="https://www.mozilla.org">
    <style type="text/css">
      .outer {
        border: 1px solid black;
        width: 100px;
        height: 100px;
      }

      .inner {
        margin-left: 50px;
        margin-top: 20px;
        width: 50px;
        height: 50px;
        background-color: purple;
      }
    </style>
  </head>
  <body>
    <div class="outer"><div class="inner"></div></div>
    <div class="outer"><div class="inner"></div></div>
    <div class="outer"><div class="inner"></div></div>
    <div class="outer"><div class="inner"></div></div>
  </body>
</html>
